The proposed research represents a continuation of efforts involving critical evaluation of that immunocontraceptive approach to fertility regulation based upon use of specific component present in pig zonage pellucidae as target antigen. Part I involves the active heteroimmunization of female squirrel monkeys with a biochemically purified pig zona antigen (PPZA) previously demonstrated to elicit antibodies having contraceptive potential in the human and non-human primate. The effect of such immunization on squirrel monkey fertility will be evaluated as well as the monitoring of the resulting immune response. Anti-PPZA activity against both homologous (i.e. PPZA and pig zonae) and heterologous (i.e. squirrel monkey zonae) antigens will be monitored By RIA and by other standard tests such as immunofluorescence and inhibition of sperm binding to antibody treated zones. Part II involves the biochemical characterization of the PPZA immunogenin respect ot the topographical arrangement of major structural features such as antigenic determinants, cysteine/cystine residues and carbohydrate side chains. In addition, structural analysis of the carbohydrate side chains will be undertaken. Positive findings from the biological aspects of the proposed research would greatly encourage continued consideration of the PPZA antigen - antibody system as a contraceptive approach for human application while the biochemical portion would provide both critical and required information pertaining to structural characterization of the PPZA immunogen.